"A 1960 study survey of 875 eight-year-olds in New York, a strikingly positive relationship children's viewing of violence on TV and their levels of aggression. Ten year later, the researchers re-interviewed more than 50% of their original subjects and found a strong relationships between the level of viewing media violence at age 8 years and a history of aggression at age 19 year, even when intelligence quotient (IQ), social status, parental aggression, social and geographic mobility, church attendance, and child's baseline aggression level were controlled. The researchers, returned to their 30-year-old subjects 12 years later and found that the greater the amount of violet TV watched by the subjects at 8 years, the more aggressive they were while under the influence of alcohol, the more harshly they disciplined their children, and the more serious were the crimes of which they had been convicted."
Source: Pediatrics in Review, August 2006, page 292
Comment: If we want our children to behave well and be excellent in school, parents should limit TV time or better still throw your TV in the window. One parent in my practice literally threw their TV set out of the door. He ended watching football at their friend's house. The children's performance in school improved.